JP2007283880A - Travel control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce behavior changes of a vehicle, to improve travel performance of the vehicle and to make a driver feel less odd by controlling the steering angle of a steered wheel to reduce influence imparted on the vehicle by a toe change of a wheel by roll steering. <P>SOLUTION: A target steering angle δft of a front wheel is calculated to attain a prescribed steering characteristic (S320). Change amount Δδf of the steering angle of the front wheel and change amount Δδr of the steering angle of a rear wheel caused by the roll steering are calculated (S330, 335, 340, 345). Based on the change amount Δδf and Δδr of the steering angle, target correction amount Δδft of the steering angle of the front wheel is calculated to cancel a change of a yaw rate γ of the vehicle caused by the toe change of the wheel by the roll steering (S350). The target steering angle δft of the front wheel is corrected to be the sum of the target steering angle δft of the front wheel and the correction amount Δδft of the steering angle of the front wheel (S360). A turning angle variable device 34 is controlled so that the steering angle δf of the front wheel may be the target steering angle δft (S370, 380). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a travel control device for a vehicle, and more particularly to a travel control device for a vehicle including a steering wheel steering angle varying device capable of turning a steered wheel without depending on a driver's steering.

As one of travel control devices for vehicles such as automobiles, for example, as described in Patent Document 1 below, a front wheel side active stabilizer device and a rear wheel side active stabilizer device that change roll rigidity are provided, and a front wheel side active stabilizer is provided. By controlling the roll rigidity of the front wheel side and the rear wheel side by the device and the rear wheel side active stabilizer device, it is configured to improve the turning performance of the vehicle at the beginning of turning and the convergence property of the vehicle at the end of turning. A traveling control device is conventionally known. According to such a travel control device, the turning performance of the vehicle at the beginning of turning and the convergence of the vehicle at the end of turning are improved, so that the turning performance of the vehicle can be improved.
JP-A-9-183306

  Generally, in a vehicle such as an automobile, the wheel is supported by a suspension arm pivotally supported at one end and pivotally attached to a wheel support member at the other end. A phenomenon in which toe changes, that is, roll steer occurs. This roll steer occurs only momentarily during normal driving of the vehicle, but when the vehicle is traveling in a crosswind condition or when traveling on a traveling road with a sloping road surface, The bounce and rebound state continues, and the degree of roll steer varies depending on the bounce of the wheel, the degree of rebound, in other words, the roll amount of the vehicle.

  Therefore, the degree of roll steer and the amount of change in wheel toe vary depending on the rolling condition of the vehicle, and therefore the driving behavior of the vehicle differs. Therefore, the driving performance of the vehicle when the vehicle rolls, especially the straight driving performance and the course Traceability may deteriorate, and the driver may feel uncomfortable due to this. Note that this problem cannot be solved even by the travel control device described in Patent Document 1.

The present invention has been made in view of the above-described problem of roll steer in a conventional vehicle, and a main object of the present invention is to reduce the influence of wheel toe change caused by roll steer on the vehicle. By controlling the steering angle of the steered wheels, it is possible to reduce changes in the behavior of the vehicle due to roll steer, to improve the running performance of the vehicle, and to reduce the uncomfortable feeling that the driver learns.
[Means for Solving the Problems and Effects of the Invention]

  According to the present invention, the main problem described above is the vehicle travel control apparatus having the steering wheel steering angle varying means capable of turning the steered wheels without depending on the configuration of claim 1, that is, the driver's steering. And means for estimating the roll amount of the vehicle, and the steering angle of the steered wheels by the steered wheel steer angle varying means so as to suppress a change in the behavior of the vehicle due to roll steer based on the estimated roll amount of the vehicle. It is achieved by a vehicle travel control device characterized by comprising control means for controlling the vehicle.

  According to the configuration of the first aspect, the roll amount of the vehicle is estimated, and the steered wheel is steered by the steered wheel steering angle varying means so as to suppress the change in the behavior of the vehicle due to the roll steer based on the estimated roll amount of the vehicle. Therefore, even when the vehicle rolls and a toe change occurs due to roll steer on the wheels, the behavior of the vehicle due to roll steer is controlled by controlling the steered angle of the steered wheels by the steered wheel rudder angle varying means. Changes can be reliably suppressed.

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the control means is a vehicle caused by roll steer based on the estimated roll amount of the vehicle. A correction turning amount of the steered wheel for suppressing a change in yaw rate is calculated, and the steering wheel rudder angle varying means is controlled based on the correction turning amount (configuration of claim 2). .

  According to the configuration of the second aspect, the corrected turning amount of the steered wheel for suppressing the change in the yaw rate of the vehicle due to the roll steer is calculated based on the estimated roll amount of the vehicle, and the corrected turning amount is calculated. Since the steering wheel steering angle variable means is controlled based on the vehicle wheel, the toe change amount due to the roll steer of each wheel is calculated based on the roll amount of the vehicle, or the roll of each wheel is calculated based on the bounce amount and rebound amount of the wheel. Without calculating the toe change amount due to the steer, it is possible to calculate the corrected steered wheel steering amount for suppressing the change in the yaw rate of the vehicle due to the roll steer, and thereby the vehicle due to the roll steer Therefore, it is possible to easily control the steering angle of the steered wheels to suppress the change in the yaw rate.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1 or 2, the means for estimating the roll amount of the vehicle controls the roll stiffness of the vehicle. And an active stabilizer device for suppressing the roll of the vehicle, and configured to estimate the roll amount of the vehicle based on the operation of the active stabilizer device (configuration of claim 3).

  According to the configuration of the third aspect, the means for estimating the roll amount of the vehicle includes the active stabilizer device that suppresses the roll of the vehicle by controlling the roll rigidity of the vehicle, and based on the operation of the active stabilizer device, the vehicle Since the roll amount is estimated, in a vehicle equipped with an active stabilizer device, the roll amount of the vehicle is obtained without providing a means for detecting the roll amount of the vehicle or a means for detecting the bounce amount and the rebound amount of the wheel. And the configuration of the travel control device can be simplified.

  According to the present invention, in any one of the above-described configurations, the steering wheel rudder angle varying means is a front wheel rudder angle varying means, and the active stabilizer device includes a front wheel side active stabilizer device and a rear wheel stabilizer. The means for estimating the roll amount of the vehicle including a wheel side active stabilizer device estimates the roll amount on the front wheel side of the vehicle based on the operation of the front wheel side active stabilizer device, and operates the rear wheel side active stabilizer device. The control means estimates the front wheel-side roll amount based on the front wheel-side roll amount and the rear wheel-side roll amount, and the front-wheel corrected steering amount for suppressing changes in vehicle behavior based on the rear-wheel-side roll amount. The control means is configured to control the front wheel steering angle varying means on the basis of the corrected turning amount of the front wheels (configuration of claim 4).

  According to the configuration of the fourth aspect, the roll amount on the front wheel side of the vehicle is estimated based on the operation of the front wheel side active stabilizer device, and on the rear wheel side of the vehicle based on the operation of the rear wheel side active stabilizer device. A roll amount is estimated, a front wheel corrected steering amount that suppresses changes in vehicle behavior is calculated based on the front wheel side roll amount and a rear wheel side roll amount, and a front wheel steering angle is calculated based on the front wheel corrected steering amount. Since the variable means is controlled, the front wheel for suppressing the change in the behavior of the vehicle without calculating the toe change amount due to the roll steer of the front wheel and the rear wheel based on the roll amount on the front wheel side and the roll amount on the rear wheel side. It is possible to calculate the corrected turning amount.

  According to the present invention, in any one of the above-described configurations, the steering wheel rudder angle varying unit includes a front wheel rudder angle varying unit and a rear wheel rudder angle varying unit, and the active stabilizer device includes: The vehicle includes a front wheel side active stabilizer device and a rear wheel side active stabilizer device, and the means for estimating the roll amount of the vehicle estimates the roll amount on the front wheel side of the vehicle based on the operation of the front wheel side active stabilizer device, and The roll amount on the rear wheel side of the vehicle is estimated based on the operation of the wheel side active stabilizer device, and the control means calculates the corrected steered amount of the front wheel that suppresses the change in toe of the front wheel based on the roll amount on the front wheel side. And calculating a corrected turning amount of the rear wheel that suppresses rear wheel toe change based on the roll amount on the rear wheel side, and the control means is based on the corrected turning amount of the front wheel. Accordingly, the front wheel rudder angle varying means is controlled, and the rear wheel rudder angle varying means is controlled on the basis of the corrected turning amount of the rear wheel (structure of claim 5).

  According to the configuration of the fifth aspect, the roll amount on the front wheel side of the vehicle is estimated based on the operation of the front wheel side active stabilizer device, and on the rear wheel side of the vehicle based on the operation of the rear wheel side active stabilizer device. A roll amount is estimated, a front wheel corrected turning amount that suppresses front wheel toe change is calculated based on the front wheel side roll amount, and a rear wheel toe change is suppressed based on the rear wheel side roll amount. The rear wheel corrected turning amount is calculated, the front wheel steering angle varying means is controlled based on the front wheel corrected turning amount, and the rear wheel steering angle varying means is controlled based on the rear wheel corrected steering amount. Therefore, correction of front and rear wheels to suppress changes in vehicle behavior without calculating toe change due to roll steer of front wheels and rear wheels based on roll amounts on the front wheels and rear wheels. It is possible to calculate the turning amount Compared to the case where the control amount of the steering angle that suppresses changes in vehicle behavior due to roll steer is distributed to the front wheels and rear wheels at a predetermined ratio, the corrected turning amount of the front wheels and rear wheels can be calculated easily. can do.

  According to the present invention, in any one of the above-described configurations, the active stabilizer device includes a two-divided stabilizer and an actuator with a built-in electric motor that relatively rotates the torsion bar of the stabilizer. The control means is configured to estimate a roll amount based on a control current for the electric motor (configuration of claim 6).

According to the configuration of the sixth aspect, the active stabilizer device includes the two-divided stabilizer and the actuator with a built-in motor that relatively rotates the torsion bar of the stabilizer, and the roll amount is estimated based on the control current for the motor. Therefore, as will be described in detail later, the roll amount of the vehicle can be easily estimated.
[Preferred embodiment of problem solving means]

  According to one preferable aspect of the present invention, in the configuration according to any one of the first to sixth aspects, the control means estimates the toe change amount of the wheel based on the estimated roll amount of the vehicle, and changes the toe change. The steering angle of the steered wheels is controlled by the steered wheel rudder angle varying means so as to cancel the influence of the amount on the behavior change of the vehicle (preferred aspect 1).

  According to another preferable aspect of the present invention, in the configuration of the preferable aspect 1, the control means is configured to have a storage means for storing a relationship between the roll amount of the vehicle and the toe change amount of the wheel. (Preferred embodiment 2).

  According to another preferred aspect of the present invention, in the configuration according to any one of the first to sixth aspects or the preferred aspect 1 or 2, the control means sets the steering angle for achieving a predetermined steering characteristic. The steering angle of the steered wheels is controlled by the steered wheel rudder angle varying means based on the sum of the control amount and the control amount of the rudder angle for suppressing the vehicle behavior change caused by the roll steer (preferred aspect) 3).

  According to another preferred embodiment of the present invention, in the structure of claim 6 or any of preferred embodiments 1 to 3, the control means includes a relative rotation angle of the two stabilizers by the actuator and a control current for the motor. It is comprised so that a roll amount may be estimated based on (preferred aspect 4).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a vehicle travel control apparatus according to a first embodiment of the present invention applied to a vehicle having an active stabilizer device on the front wheel side and the rear wheel side and capable of controlling the steering angle of the front wheel.

  In FIG. 1, 10FL and 10FR indicate the left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR indicate the left and right rear wheels of the vehicle 12, respectively. An active stabilizer device 16 is provided between the left and right front wheels 10FL and 10FR, and an active stabilizer device 18 is provided between the left and right rear wheels 10RL and 10RR. The active stabilizer devices 16 and 18 function as roll stiffness changing means for applying an anti-roll moment to the vehicle (vehicle body) and increasing / decreasing the roll stiffness on the front wheel side and the rear wheel side as required.

  The active stabilizer device 16 is integrally connected to a pair of torsion bar portions 16TL and 16TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and to the outer ends of the torsion bar portions 16TL and 16TR, respectively. And a pair of arm portions 16AL and 16AR. The torsion bar portions 16TL and 16TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 16AL and 16AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 16TL and 16TR, respectively, and the outer ends of the arm portions 16AL and 16AR are respectively left and right through rubber bush devices not shown in the drawing. The front wheels 10FL and 10FR are connected to suspension members 14FL and 14FR such as suspension arms.

  The active stabilizer device 16 has an actuator 20F between the torsion bar portions 16TL and 16TR. Actuator 20F has a built-in electric motor, and rotationally drives a pair of torsion bar portions 16TL and 16TR as necessary, so that torsional stress is generated when the left and right front wheels 10FL and 10FR bounce and rebound in opposite phases to each other. Thus, the force to suppress the bounce and rebound of the wheel is changed, thereby increasing or decreasing the anti-roll moment applied to the vehicle at the position of the left and right front wheels, and variably controlling the roll rigidity of the vehicle on the front wheel side.

  Similarly, the active stabilizer device 18 has a pair of torsion bar portions 18TL and 18TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and the outer ends of the torsion bar portions 18TL and 18TR, respectively. It has a pair of arm portions 18AL and 18AR connected together. The torsion bar portions 18TL and 18TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 18AL and 18AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 18TL and 18TR, respectively, and the outer ends of the arm portions 18AL and 18AR are respectively left and right through rubber bushing devices not shown in the drawing. The suspension members 14RL and 14RR such as the suspension arms of the rear wheels 10RL and 10RR are connected.

  The active stabilizer device 18 has an actuator 20R between the torsion bar portions 18TL and 18TR. The actuator 20R has a built-in electric motor, and if necessary, the pair of torsion bar portions 18TL and 18TR are driven to rotate relative to each other, so that the left and right rear wheels 10RL and 10RR bounce and rebound in opposite phases. The force that suppresses the bounce and rebound of the wheel is changed by the stress, whereby the anti-roll moment applied to the vehicle at the positions of the left and right rear wheels is increased and decreased, and the roll rigidity of the vehicle on the rear wheel side is variably controlled.

  Since the structures of the active stabilizer devices 16 and 18 do not form the gist of the present invention, any structure known in the art can be used as long as the roll rigidity of the vehicle can be variably controlled. However, for example, the active stabilizer device described in the specification and drawings of Japanese Patent Application No. 2003-324212 (reference number PA03-374) relating to the application of the present applicant, that is, a drive gear fixed to the inner end of one torsion bar portion is provided. An electric motor having an attached rotating shaft and a driven gear that is fixed to the inner end of the other torsion bar portion and meshes with the driving gear. The driving gear and the driven gear transmit the rotation of the driving gear to the driven gear. The active stabilizer device is preferably a gear that does not transmit the rotation of the driven gear to the drive gear.

  The actuators 20F and 20R of the active stabilizer devices 16 and 18 are controlled by the electronic control device 22 controlling the control current for the motor. Although not shown in detail in FIG. 1, the electronic control unit 22 includes a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  In the illustrated embodiment, as shown in FIG. 1, the left and right front wheels 10FL and 10FR are driven in response to the operation of the steering wheel 24 by the driver. 26 is steered by the rack bar 28 and the tie rods 30L and 30R.

  The steering wheel 24 is drivingly connected to the pinion shaft 40 of the power steering device 26 via an upper steering shaft 32, a turning angle varying device 34, a lower steering shaft 36, and a universal joint 38. In the illustrated embodiment, the turning angle varying device 34 is connected to the lower end of the upper steering shaft 32 on the side of the housing 34A and is connected to the upper end of the lower steering shaft 36 on the side of the rotor 34B. An electric motor 42 for turning driving is included.

  Thus, the steering angle varying device 34 drives the lower steering shaft 36 to rotate relative to the upper steering shaft 32, so that the ratio of the steering angles of the left and right front wheels 10 FL and 10 FR, which are the steering wheels, with respect to the rotation angle of the steering wheel 24. That is, it functions as a steering gear ratio variable means for changing the steering transmission ratio (the reciprocal of the steering gear ratio), and the left and right front wheels 10FL and 10FR are auxiliary-steered relative to the steering wheel 14 for the purpose of vehicle travel control. It functions as an automatic steering device that is driven, and is controlled by the electronic control device 44. Although not shown in detail in FIG. 1, the electronic control unit 44 also has a CPU, a ROM, a RAM, and an input / output port unit, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  As shown in FIG. 1, the electronic control unit 22 includes a signal indicating the vehicle lateral acceleration Gy detected by the lateral acceleration sensor 48, a signal indicating the vehicle speed V detected by the vehicle speed sensor 50, a rotation angle sensor 52F, Signals indicating the actual rotation angles φF and φR of the actuators 20F and 20R detected by 52R are input.

  On the other hand, the electronic control unit 44 indicates the signal indicating the steering angle θ detected by the steering angle sensor 56 and the relative rotation angle θre detected by the rotation angle sensor 58, that is, the relative rotation angle of the lower steering shaft 36 with respect to the upper steering shaft 32. The signal shown is input. The electronic control units 22 and 44 communicate with each other and exchange necessary signals.

  The lateral acceleration sensor 48 and the steering angle sensor 56 detect the lateral acceleration Gy and the steering angle θ with positive values generated when the vehicle turns left, and the rotation angle sensor 58 detects the relative turning of the left and right front wheels in the left turning direction. The relative rotation angle θre is detected with the case being positive.

  The electronic control unit 22 estimates the roll moment acting on the vehicle based on at least the lateral acceleration Gy of the vehicle according to the flowchart shown in FIG. 2, and cancels the roll moment when the magnitude of the roll moment is greater than or equal to the reference value. The target anti-roll moment Mat of the vehicle is calculated so that the anti-roll moment in the direction increases. The electronic control unit 22 calculates the target anti-roll moment Maft of the front wheel and the target anti-roll moment Mart of the rear wheel based on the target anti-roll moment Mat and the target roll stiffness distribution ratio Rmf of the front wheel, and the target anti-roll moment Maft and Mart. Based on the above, the target rotation angles φFt and φRt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are calculated, respectively, and control is performed so that the rotation angles φF and φR of the actuators 20F and 20R become the corresponding target rotation angles φFt and φRt, respectively. Thus, the roll of the vehicle at the time of turning or the like is reduced with a preferable roll rigidity distribution ratio of the front and rear wheels.

  Thus, the active stabilizer devices 16 and 18, the electronic control device 22, the lateral acceleration sensor 48, and the like function as a roll stiffness variable device that increases or decreases the roll stiffness of the vehicle by increasing or decreasing the anti-roll moment when an excessive roll moment acts on the vehicle. To do. The electronic control unit 22 outputs signals indicating control currents Isf and Isr to the motors of the actuators 20F and 20R to the electronic control unit 44.

  Further, the electronic control unit 44 calculates the target steering gear ratio Rgt based on the vehicle speed V according to the flowchart shown in FIG. 3, and the front wheel based on the steering angle θ indicating the driver's steering operation amount and the target steering gear ratio Rgt. The target rudder angle δft of is calculated. The electronic control unit 44 estimates the roll angle αf on the front wheel side and the roll angle αr on the rear wheel side of the vehicle based on the control currents Isf and Isr for the motors of the actuators 20F and 20R, respectively, and roll angles αf and αr. On the basis of these, the amount of change Δδf and Δδr in the steering angle of the front wheels and the rear wheels caused by roll steer is calculated.

  Then, the electronic control unit 44 calculates a target correction amount Δδft of the front wheel steering angle based on the change amounts Δδf and Δδr of the front and rear wheels, corrects the target steering angle δft of the front wheels to δtf + Δδtf, and steers the front wheels. By controlling the turning angle varying device 34 so that the angle δf becomes the corrected target steering angle δft of the front wheel, a change in vehicle behavior due to roll steer is prevented.

As shown in FIG. 8, the torsion angle from the inner end of the left torsion bar portion 64TL of the active stabilizer device 60 representing the active stabilizer devices 16 and 18 to the outer end of the arm portion 64AL is φ1, and the right side The torsion angle from the inner end of the torsion bar portion 64TR to the outer end of the arm portion 64AR is φ2, the torsional rigidity from the inner end of the left torsion bar portion 64TL to the outer end of the arm portion 64AL is K1, and the right torsion The torsional rigidity from the inner end of the bar portion 64TR to the outer end of the arm portion 64AR is K2, the length of the arm portions 64AL and 64AR is R, the external force acting on the outer ends of the arm portions 64AL and 64AR is F, and the actuator If the control current for the motor 62 is Is and the torque constant Ka of the actuator 62, the following equations 1 and 2 are established.
φ1 = FR / K1 = IsKa / K1 (1)
φ2 = FR / K2 = IsKa / K2 (2)

When the rotation angle of the actuator 62 is φa, the roll angle α of the vehicle at the position where the active stabilizer device 60 is provided is expressed by the following Equation 3.
α = φa + φ1 + φ2
= Φa + IsKa (K1 + K2) / (K1K2) (3)

Accordingly, in the illustrated first embodiment, the values corresponding to the torsional stiffness K1 of the active stabilizer devices 16 and 18 are K1f and K1r, the values corresponding to the torsional stiffness K2 are K2f and K2r, and the torques of the actuators 20F and 20R. As constants Kaf and Kar, the electronic control unit 44 uses the actual rotation angles φF and φR of the actuators 20F and 20R and the control currents Isf and Isr for the motors of the actuators 20F and 20R, respectively, according to the following equations 4 and 5 to The roll angle αf on the side and the roll angle αr on the rear wheel side are calculated.
αf = φF + IsfKaf (K1f + K2f) / (K1fK2f) (4)
αr = φR + IsrKar (K1r + K2r) / (K1rK2r) (5)

  In general, as indicated by a solid line in FIG. 9, the front wheels steer in the toe-in direction when bound and steer in the toe-out direction when rebounded. Conversely, as indicated by the broken line in FIG. 9, the rear wheel steers in the toe-out direction when bound and steer in the toe-in direction when rebounding. Therefore, the relationship between the roll angle αf on the front wheel side of the vehicle and the toe change amount of the front wheel, that is, the change amount Δδf of the steering angle is the relationship shown in FIG. 7A, and the roll angle αr on the rear wheel side of the vehicle. And the rear wheel toe change amount, that is, the steering angle change amount Δδr, is the relationship shown in FIG. 7B, the electronic control unit 44 determines the roll angle αf and the rear wheel on the front wheel side of the vehicle. The change amount Δδf of the steering angle of the front wheels and the change amount Δδr of the steering angle of the rear wheels are calculated from the maps corresponding to the graphs shown in FIGS. 7A and 7B, respectively, based on the roll angle αr on the side. To do.

Also, the transfer function from the steering angle δf of the front wheel to the yaw rate γ of the vehicle by the steering operation of the driver is Gyf (δf), and the yaw rate of the vehicle is calculated from the change amount Δδf of the steering angle of the front wheels and the change amount Δδr of the steering angle of the rear wheels. If the transfer function to the vehicle is Gyf (Δδf) and Gyr (Δδr), and the amount of correction of the steering angle of the front wheels by the turning angle varying device 34 is Δδvf, the transfer function to the vehicle yaw rate is Gyf (Δδvf). The yaw rate γ is expressed by Equation 6 below.
γ = Gyf (δf) + Gyf (Δδf) + Gyr (Δδr) + Gyf (Δδvf) (6)

From the above formula 6, if the following formula 7 is established, that is, if the steering angle correction amount Δδvf of the front wheel by the turning angle varying device 34 is controlled to be a value represented by the following formula 8, the roll steer It can be seen that a change in the yaw rate γ of the vehicle, that is, a change in behavior can be prevented.
Gyf (Δδvf) = − Gyf (Δδf) −Gyr (Δδr) (7)
Δδvf = −Δδf− (Gyr / Gyf) Δδr (8)

Therefore, in the illustrated first embodiment, the electronic control unit 44 uses the amount of change Δδf in the steering angle of the front wheels and the amount of change Δδr in the steering angle of the rear wheels according to the following formula 9 to obtain a target correction amount for the steering angle of the front wheels. Δδft is calculated.
Δδft = −Δδf− (Gyr / Gyf) Δδr (9)

  Next, the vehicle travel control in the illustrated embodiment 1 will be described with reference to the flowcharts shown in FIGS. FIGS. 2 and 3 are flow charts showing a roll rigidity control routine and a front wheel rudder angle control routine, respectively. Each control is started by closing an ignition switch not shown in the figure, and is performed at predetermined time intervals. Will be executed repeatedly.

  In step 210 of the roll stiffness control routine shown in FIG. 2, a signal indicating the vehicle lateral acceleration Gy is read. In step 220, the front wheel speed is increased so that the vehicle speed V increases. The target roll stiffness distribution ratio Rmf is calculated as a value larger than 0 and smaller than 1.

In step 230, for example, the target anti-roll moment Mat is calculated based on the lateral acceleration Gy of the vehicle so that the target anti-roll moment Mat increases as the lateral acceleration Gy of the vehicle increases. The target anti-roll moment Maft for the front wheels and the target anti-roll moment Mart for the rear wheels are calculated according to the following equations 10 and 11, respectively.
Maft = RmfMat (10)
Mart = (1-Rmf) Mat (11)

  In step 250, the target rotational angles φft and φrt of the actuators 20F and 20R of the active stabilizer devices 16 and 18 are calculated based on the front wheel target anti-roll moment Maft and the rear wheel target anti-roll moment Mart, respectively. In this case, the rotation angles φf and φr of the actuators 20F and 20R are controlled to be the target rotation angles φft and φrt, respectively. In step 270, signals indicating the control currents Isf and Isr for the motors of the actuators 20F and 20R are obtained. It is output to the electronic control unit 44.

In step 310 of the front wheel steering angle control routine shown in FIG. 3, a signal indicating the steering angle θ is read, and in step 320, the vehicle speed V is shown in FIG. 6. A target steering gear ratio Rgt is calculated from a map corresponding to the graph, and a target steering angle δft of the front wheels for achieving a predetermined steering characteristic is calculated according to the following formula 12.
δft = θ / Rgt (12)

  Note that the standard steering gear ratio is Rgo (a positive constant), and the target steering angle δft is a steering angle δw (= θ / Rgo) corresponding to the driver's steering operation and control steering to achieve a predetermined steering characteristic. It is the sum with the angle δc. Further, the control of the steering characteristic itself does not form the gist of the present invention, and the target steering gear ratio Rgt may be calculated in an arbitrary manner known in the art. For example, the transient response of the vehicle to the steering can be calculated. In order to improve, it may change also with steering speed (change rate of steering angle (theta)).

  In step 330, the roll angle αf on the front wheel side of the vehicle is calculated according to the above equation 4 based on the actual rotation angle φF of the actuator 20F and the control current Isf for the motor of the actuator 20F. In step 335, the roll angle is calculated. Based on αf, a change amount Δδf of the steering angle of the front wheels caused by roll steer is calculated from a map corresponding to the graph shown in FIG.

  Similarly, in step 340, the roll angle αr on the rear wheel side of the vehicle is calculated according to the above equation 5 based on the actual rotation angle φR of the actuator 20R and the control current Isr for the motor of the actuator 20R. In this case, the amount of change Δδr in the steering angle of the rear wheels caused by the roll steer is calculated from the map corresponding to the graph shown in FIG. 7B based on the roll angle αr.

  In step 350, the target correction amount Δδft of the front wheel steering angle is calculated according to the above equation 9 based on the change amount Δδf of the front wheel steering angle and the rear wheel steering angle change Δδr. The front wheel target rudder angle δft is corrected so as to be the sum of the front wheel target rudder angle δft calculated in step 320 and the front wheel rudder angle correction amount Δδft calculated in step 350.

  In step 370, based on the target steering angle δft of the front wheels, the target relative rotation angle of the steering angle varying device 34 for changing the steering angle δf of the front wheels to the target steering angle δft in a manner known in the art. θret is calculated, and in step 380, the steered angle varying device 34 is controlled so that the relative rotational angle θre of the steered angle varying device 34 becomes the target relative rotational angle θret. Control is performed to achieve the target rudder angle δft.

  Thus, according to the illustrated first embodiment, the target roll stiffness distribution ratio Rmf is calculated in step 220, the target anti-roll moment Mat is calculated in step 230 based on the lateral acceleration Gy of the vehicle, and in step 240. Then, the target anti-roll moment Maft of the front wheel and the target anti-roll moment Mart of the rear wheel for achieving the target anti-roll moment Mat at the target roll stiffness distribution ratio Rmf are calculated, and in steps 250 and 260, the target anti-roll moment is calculated. The active stabilizer devices 16 and 18 are controlled so that Maft and Mart are achieved, thereby preventing excessive rolling of the vehicle.

  Further, according to the illustrated embodiment 1, in step 320, the target steering gear ratio Rgt is calculated based on the vehicle speed V, and the target steering angle δft of the front wheels for achieving predetermined steering characteristics is calculated. In 330 and 335, the change amount Δδf of the front wheel steering angle caused by roll steer is calculated, and in steps 340 and 345, the change amount Δδr of the rear wheel steering angle caused by roll steer is calculated.

  Then, in step 350, the front wheel for canceling the change in the yaw rate γ of the vehicle due to the wheel toe change due to the roll steer based on the change Δδf in the front wheel rudder angle and the change Δδr in the rear wheel rudder angle. The steering angle target correction amount Δδft is calculated, and in step 360, the front wheel target steering angle δft is corrected so as to be the sum of the front wheel target steering angle δft and the front wheel steering angle correction amount Δδft. In 380, the turning angle varying device 34 is controlled so that the steering angle δf of the front wheels becomes the target steering angle δft.

  Therefore, according to the illustrated embodiment 1, the steering angle of the front wheels can be controlled by the turning angle varying device 34 so as to cancel the change in the yaw rate γ of the vehicle due to the change in the wheel toe caused by the roll steer. Regardless of the rolling condition of the vehicle, it is possible to reliably prevent changes in the behavior of the vehicle due to roll steer, improve the running performance of the vehicle, and prevent the driver from feeling uncomfortable due to the change in the behavior of the vehicle. it can.

  In particular, according to the first embodiment shown in the drawing, the target rudder angle δft of the front wheel for achieving a predetermined steering characteristic is calculated in step 320, and the target rudder angle δft of the front wheel and the rudder angle of the front wheel are calculated in step 360. The target steering angle δft of the front wheels is corrected so as to be the sum of the correction amount Δδft of the steering wheel, and the steering angle varying device 34 is controlled in steps 370 and 380 so that the steering angle δf of the front wheels becomes the target steering angle δft. Therefore, it is possible to reliably prevent a change in the behavior of the vehicle due to roll steer while achieving a predetermined steering characteristic.

  Further, according to the illustrated embodiment 1, since only the steering angle of the front wheels is controlled, the control of the steering angle of the rear wheels is unnecessary, and therefore the rear wheel steering device is also unnecessary. Further, the steering angle of the steered wheels can be easily controlled as compared with the case where the steered angle of the rear wheels is also controlled.

  In the illustrated embodiment 1, the front wheel steering angle correction amount Δδft for canceling the change in the vehicle yaw rate γ caused by the wheel toe change due to the roll steer is calculated to achieve a predetermined steering characteristic. The target rudder angle δft of the front wheels is corrected so as to be the sum of the target rudder angle δft of the front wheels and the correction amount Δδft of the rudder angle of the front wheels, but to achieve a predetermined steering characteristic Control of the steering angle of the front wheels is omitted, and the steering angle of the front wheels is controlled based only on the control amount of the steering angle of the front wheels for canceling the change in the yaw rate γ of the vehicle caused by the wheel toe change due to roll steer. It may be modified as follows.

  FIG. 4 is a schematic configuration diagram showing a second embodiment of the vehicle travel control device according to the present invention applied to a vehicle capable of controlling the steering angles of the front wheels and the rear wheels. In FIG. 4, the same members as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

  In the second embodiment, the left and right rear wheels 10RL and 10RR are separated from the left and right front wheels 10FL and 10FR by the hydraulic or electric power steering device 54 of the rear wheel steering device 52 and the tie rods 56L and 56R. The rear wheel steering device 52 is controlled by the electronic control device 44 through 56R.

  The electronic control unit 44 calculates the target rudder angle δft of the front wheels based on the vehicle speed V so that a predetermined steering characteristic is achieved, and also based on the steering angle θ and the vehicle speed V, as in the case of the first embodiment. The rear wheel target rudder angle δrt is calculated in a manner known in the art.

  Further, the electronic control unit 44 estimates the roll angle αf on the front wheel side and the roll angle αr on the rear wheel side of the vehicle based on the control currents Isf and Isr for the motors of the actuators 20F and 20R, respectively, and the roll angle αf and Based on αr, change amounts Δδf and Δδr of the steering angles of the front wheels and the rear wheels caused by roll steer are calculated.

In the second embodiment, since the rear wheel steering angle is controlled by the rear wheel steering device 52, the transfer function to the yaw rate of the vehicle is calculated from the rear wheel steering angle correction amount Δδvr by the rear wheel steering device 52. Assuming Gyf (Δδvr), the yaw rate γ of the vehicle is expressed by Equation 13 below.
γ = Gyf {δf} + Gyf (Δδf) + Gyr (Δδr)
+ Gyf (Δδvf) + Gyf (Δδvr) (13)

From the above formula 13, the following formulas 14 and 15 are satisfied, that is, the steering wheel correction angle Δδvf by the turning angle varying device 34 becomes a value represented by the following formula 16 and the rear wheel steering device 52. It can be understood that the change in the yaw rate γ of the vehicle due to the roll steer, that is, the change in the behavior, can be prevented by controlling the correction amount Δδvr of the steering angle of the rear wheel due to
Gyf (Δδvf) = − Gyf (Δδf) (14)
Gyf (Δδvr) = − Gyr (Δδr) (15)
Δδvf = −Δδf (16)
Δδvr = −Δδr (17)

Therefore, in the illustrated second embodiment, the electronic control unit 44 uses the front wheel steering angle change amount Δδf and the rear wheel steering angle change amount Δδr according to the following equations 18 and 19 to determine the front wheel steering angle target. A correction amount Δδft and a rear wheel steering angle target correction amount Δδrt are calculated.
Δδft = −Δδf (18)
Δδrt = −Δδr (19)

  Then, the electronic control unit 44 corrects the target steering angle δft of the front wheels to δft + Δδft and corrects the target steering angle δrt of the rear wheels to δrt + Δδrt, so that the steering angle δf of the front wheels becomes the corrected target steering angle δft of the front wheels. By controlling the turning angle varying device 34 and controlling the rear wheel steering device 52 so that the rear wheel steering angle δr becomes the corrected rear wheel target steering angle δrt, the behavior of the vehicle due to roll steer Prevent change.

  In the second embodiment, the active stabilizer devices 16 and 18 are controlled by the electronic control device 22 according to the control routine shown in FIG. 2 as in the first embodiment.

  FIG. 5 is a flowchart showing a routine for controlling the steering angles of the front wheels and the rear wheels in the second embodiment. The control according to the flowchart shown in FIG. 5 is also started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

  In the control routine for the steering angles of the front wheels and the rear wheels in the second embodiment, steps 510 to 580 are basically executed in the same manner as steps 310 to 380 in the first embodiment described above. In 520, the target rudder angle δft of the front wheels for achieving a predetermined steering characteristic is calculated in the same manner as in the first embodiment, and the present technology is based on the steering angle θ and the vehicle speed V. A target steering angle δrt of the rear wheel for achieving a predetermined steering characteristic is calculated in a manner known in the field.

  In step 550, the front wheel rudder angle change amount Δδf and the rear wheel rudder angle change amount Δδr based on the above-described equations 18 and 19, the front wheel rudder angle target correction amount Δδft and the rear wheel rudder angle A target correction amount Δδrt is calculated.

  In step 560, the front wheel target rudder angle δft is calculated to be the sum of the front wheel target rudder angle δft calculated in step 320 and the front wheel rudder angle correction amount Δδft calculated in step 350. Is corrected, and the rear wheel target rudder angle δrt calculated in step 320 and the rear wheel rudder steering angle correction amount Δδrt calculated in step 355 are equal to the sum. The angle δrt is corrected.

  Further, in step 380, the steering angle varying device 34 is controlled so that the steering angle δf of the front wheels becomes the target steering angle δft, and in step 390, the steering angle δr of the rear wheels becomes the target steering angle δrt. The rear wheel steering device 52 is controlled.

  Thus, according to the illustrated second embodiment, the steering angle of the front wheel is controlled by the turning angle variable device 24 so as to cancel the change in the yaw rate γ of the vehicle due to the change in the toe of the front wheel due to the roll steer, and the rear by the roll steer. The steering angle of the rear wheel can be controlled by the rear wheel steering device 52 so as to cancel the change in the yaw rate γ of the vehicle due to the change in the wheel toe, whereby the vehicle due to the roll steer regardless of the roll condition of the vehicle. It is possible to reliably prevent the change in the behavior of the vehicle, improve the running performance of the vehicle, and prevent the driver from feeling uncomfortable due to the change in the behavior of the vehicle.

  In particular, according to the illustrated second embodiment, in step 520, the target rudder angle δft of the front wheels and the target rudder angle δrt of the rear wheels for achieving a predetermined steering characteristic are calculated, and in step 560, the target rudder of the front wheels is calculated. The target rudder angle δft of the front wheels is corrected to be the sum of the rudder angle δft and the front wheel rudder angle correction amount Δδft, and the sum of the rear wheel target rudder angle δrt and the rear wheel rudder angle correction amount Δδrt. In step 570 and 580, the steered angle varying device 34 is controlled so that the front wheel rudder angle δf becomes the target rudder angle δft, and in step 390, the rear wheel target rudder angle δrt is corrected. Since the rear wheel steering device 52 is controlled so that the steering angle δr of the rear wheels becomes the target steering angle δrt, it is possible to reliably prevent a change in the behavior of the vehicle due to roll steer while achieving a predetermined steering characteristic. .

  Further, according to the illustrated second embodiment, the front wheel steering angle correction amount Δδft and the rear wheel steering angle correction amount Δδrt cancel the toe changes of the front and rear wheels caused by roll steering according to the above equations 18 and 19, respectively. As compared to the case where the control amount of the steering angle that cancels the change in the yaw rate γ of the vehicle due to roll steer is distributed at a predetermined ratio to the front wheels and the rear wheels, for example, The correction amount Δδft for the steering angle of the front wheels and the correction amount Δδrt for the steering angle of the rear wheels can be easily calculated.

  In the illustrated embodiment 2, the front wheel rudder angle correction amount Δδft and the rear wheel rudder angle correction amount Δδrt to cancel the change in the yaw rate γ of the vehicle due to the wheel toe change due to roll steer. Is calculated, the front wheel target rudder angle δft is corrected to be the sum of the front wheel target rudder angle δft and the front wheel rudder angle correction amount Δδft, and the predetermined steering characteristic is obtained. The rear wheel target rudder angle δrt is corrected so as to be the sum of the rear wheel target rudder angle δrt and the rear wheel rudder angle correction amount Δδrt. It may be modified so that the steering angles of the front wheels and the rear wheels are controlled based only on the control amounts of the steering angles of the front wheels and the rear wheels for canceling the change in the yaw rate γ of the vehicle caused by the toe change.

  Further, according to the first and second embodiments described above, the roll angle αf on the front wheel side of the vehicle is calculated based on the actual rotation angle φF of the actuator 20F and the control current Isf for the electric motor of the actuator 20F, and the actual angle of the actuator 20R is calculated. Since the roll angle αr on the rear wheel side of the vehicle is calculated based on the rotation angle φR and the control current Isr for the electric motor of the actuator 20R, there is no need for a means for detecting the roll angle of the vehicle such as a roll angle sensor. The roll angle αf on the side and the roll angle αr on the rear wheel side can be calculated, and the configuration of the travel control device can be simplified.

  Further, according to the first and second embodiments described above, the amount of change Δδf in the steering angle of the front wheels caused by roll steer is calculated based on the roll angle αf on the front wheel side of the vehicle, and the roll angle αr on the rear wheel side of the vehicle is calculated. Since the change amount Δδr of the rear wheel steering angle caused by roll steer is calculated based on the above, the change in the steering angle of the front wheel caused by roll steer without requiring means for detecting the bounce and rebound amount of each wheel The amount Δδf and the rear wheel steering angle change amount Δδr can be calculated, and the configuration of the travel control device can be simplified.

  The wheels bounce and rebound when the vehicle is decelerating and accelerating, but the right and left wheels bounce and rebound in phase with each other, so that no roll angle is generated. According to this, it is possible to reliably avoid unnecessary control of the steering angles of the front wheels and the rear wheels during deceleration or acceleration of the vehicle.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the corrected turning amount of the steered wheels for suppressing the change in the yaw rate of the vehicle due to roll steer is calculated based on the estimated roll amount of the vehicle, and the corrected turning amount is calculated. Although the steering angle of the steered wheels is controlled based on the steer amount, the corrected steered amount of the steered wheels is smaller than a value necessary to cancel the change in the yaw rate of the vehicle due to roll steer. It may be calculated as follows.

  In each of the above-described embodiments, the left and right front wheels 10FL and 10FR steer in the toe-in direction when bound, and the steering change in the toe-out direction upon rebound, and the left and right rear wheels 10RL and 10RR in the toe-out direction when bound. While it is assumed that the steering changes and the steering changes in the toe-in direction at the time of rebounding, the steering of the wheels accompanying the bounding and rebounding of the wheels may be any change.

  In each of the above-described embodiments, the roll angle αf on the front wheel side of the vehicle is calculated based on the actual rotation angle φF of the actuator 20F and the control current Isf for the motor of the actuator 20F, and the actual rotation of the actuator 20R. The roll angle αr on the rear wheel side of the vehicle is calculated on the basis of the angle φR and the control current Isr for the electric motor of the actuator 20R. The roll angle αf and the rear wheel on the front wheel side are calculated by means such as a roll angle sensor. The side roll angle αr may be corrected so as to be detected. In that case, the traveling control device of the present invention may be applied to a vehicle that does not include an active stabilizer device.

  In the above-described second embodiment, the steering angle correction amount Δδft for the front wheels and the steering angle correction amount Δδrt for the rear wheels are respectively controlled for the steering angle to cancel the change in the toe of the front wheels and the rear wheels due to roll steer. The steering angle control amount that cancels the change in the yaw rate γ of the vehicle due to roll steer is distributed to the front wheels and the rear wheels at a predetermined ratio, so that the steering angle of the front wheels can be calculated. The correction amount Δδft and the rear wheel steering angle correction amount Δδrt may be modified to be calculated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle travel control device according to the present invention applied to a vehicle having an active stabilizer device on a front wheel side and a rear wheel side and capable of controlling a steering angle of a front wheel. 3 is a flowchart showing a roll rigidity control routine in the first embodiment. 3 is a flowchart illustrating a control routine for a steering angle of a front wheel in the first embodiment. It is a schematic block diagram which shows Example 2 of the traveling control apparatus of the vehicle by this invention applied to the vehicle which has an active stabilizer apparatus in the front-wheel side and a rear-wheel side, and can control the steering angle of a front wheel and a rear wheel. 7 is a flowchart showing a control routine for a steering angle of a front wheel in the second embodiment. It is a graph which shows the relationship between the vehicle speed V and the target steering gear ratio Rgt. Graph (A) showing the relationship between the roll angle αf on the front wheel side and the change amount Δδf of the steering angle of the front wheel caused by roll steer, and the steering angle of the rear wheel caused by the roll angle αr on the rear wheel side and roll steer It is a graph (B) which shows the relationship between the variation | change_quantity (DELTA) delta of this. It is explanatory drawing which shows the point which calculates the roll angle of a vehicle based on the action | operation of an active stabilizer apparatus. It is a graph which shows the relationship between the amount of bounds and the amount of rebound, and the amount of toe change of a wheel about a front wheel (solid line) and a rear wheel (dashed line).

Explanation of symbols

16, 18 Active stabilizer device 20F, 20R Actuator 22 Electronic control device 34 Steering angle variable device 44 Electronic control device 48 Lateral acceleration sensor 50 Vehicle speed sensor 52F, 52R Rotation angle sensor 56 Steering angle sensor 58 Rotation angle sensor

Claims (6)

  A vehicle travel control device having steering wheel rudder angle varying means capable of steering a steered wheel without depending on driver's steering, wherein the vehicle roll amount is estimated, and the estimated vehicle roll amount And a control means for controlling the steering angle of the steering wheel by the steering wheel steering angle varying means so as to suppress a change in the behavior of the vehicle due to the roll steer based on the vehicle steering control device.   The control means calculates a corrected turning amount of the steering wheel for suppressing a change in the yaw rate of the vehicle due to roll steer based on the estimated roll amount of the vehicle, and based on the corrected turning amount, The vehicle travel control apparatus according to claim 1, wherein the steering wheel steering angle varying means is controlled.   The means for estimating the roll amount of the vehicle includes an active stabilizer device that suppresses the roll of the vehicle by controlling the roll stiffness of the vehicle, and estimates the roll amount of the vehicle based on the operation of the active stabilizer device. The travel control device for a vehicle according to claim 1 or 2.   The steering wheel rudder angle varying means is a front wheel rudder angle varying means, the active stabilizer device includes a front wheel side active stabilizer device and a rear wheel side active stabilizer device, and the means for estimating the roll amount of the vehicle is the front wheel side active The roll amount on the front wheel side of the vehicle is estimated based on the operation of the stabilizer device, the roll amount on the rear wheel side of the vehicle is estimated based on the operation of the rear wheel side active stabilizer device, and the control means And the control means calculates the front wheel steering angle variable based on the front wheel correction turning amount. 4. The vehicle travel control apparatus according to claim 1, wherein the vehicle travel control apparatus controls the vehicle.   The steering wheel rudder angle varying means includes front wheel rudder angle varying means and rear wheel rudder angle varying means, and the active stabilizer device includes a front wheel side active stabilizer device and a rear wheel side active stabilizer device, and estimates the roll amount of the vehicle. The means for estimating the roll amount on the front wheel side of the vehicle based on the operation of the front wheel side active stabilizer device, and estimating the roll amount on the rear wheel side of the vehicle based on the operation of the rear wheel side active stabilizer device, The control means calculates a corrected turning amount of a front wheel that suppresses a front wheel toe change based on the front wheel side roll amount, and suppresses a rear wheel toe change based on the rear wheel side roll amount. The corrected turning amount of the wheel is calculated, and the control means controls the front wheel steering angle varying means based on the corrected turning amount of the front wheel and corrects the corrected turning of the rear wheel. Running control apparatus for a vehicle according to any one of claims 1 to 3, wherein the controller controls the rear-wheel steering angle varying means based on the amount. The active stabilizer device includes a two-divided stabilizer and an actuator with a built-in electric motor that relatively rotates a torsion bar of the stabilizer, and the control means estimates a roll amount based on a control current for the electric motor. The vehicle travel control apparatus according to any one of claims 3 to 5.

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